This invention relates to certain novel 2-alkynyl-6-pyridin-2-yl-pyridazinones, 2-alkynyl-6-pyridin-2-yl-dihydropyridazinones, 2-alkynyl-6-pyrimidin-2-yl-pyridazinones and 2-alkynyl-6-pyrimidin-2-yl-dihydropyridazinones and to the use of these compounds for control of fungal pathogens of plants and mammals.
A number of dihydropyridazinones and pyridazinones and their pesticidal properties have been described in the art. U.S. Pat. Nos. 5,728,715 and 5,741,793, the disclosures of which are explicitly incorporated by reference herein, disclose a genus of 2-alkynyl-6-aryl dihydropyridazinones and pyridazinones and their use as fungicides. The apparent fungicidal mechanism of action of these compounds involves inhibition of the enzyme Δ-9 fatty acid desaturase as disclosed in WO 03/106385 A2, the disclosure of which is explicitly incorporated by reference herein. One characteristic of these compounds is the ability of some saturated fatty acids to enhance their fungitoxicity towards certain fungi as disclosed in U.S. Pat. No. 5,741,793, the disclosure of which is explicitly incorporated by reference herein. It has now been discovered that a particular subclass of the genus disclosed in '715 and '793 have greatly improved fungicidal activity.